November 25, 2018 at 2:33 am
I know this can be done or believe it can be but as I am no network specialist I am wondering what I would need to inform the customer of from an infrastructure.
A customer has two data centres. Site A and site B. I am looking to implement a Always on High Availability Group across a Primary node in site A and a replica in Site B.
The customer has stated that there network is Later three separated so there is a VLAN in each site with a /25 subnet dedicated to SQL usage. For example (10.124.x.x in site A and 10.125.x.x is site B).
With a HAG the clustering features are installed across both nodes but how does it work behind the scenes,I have to describe to the customer how they need to configure the communication/networks between both sites to enable this to work. I know back in the day the a cluster needed to be on the same network/vlan but now I believe the servers can be on different networks and availability Group listeners can be on a seprecate one also.
November 29, 2018 at 8:38 am
Unless I've misunderstood, I think the term you're looking for is a multi-subnet failover cluster?
https://docs.microsoft.com/en-us/sql/sql-server/failover-clusters/windows/sql-server-multi-subnet-clustering-sql-server?view=sql-server-2017
November 29, 2018 at 8:51 am
Andrew.weckermann - Sunday, November 25, 2018 2:33 AMI know this can be done or believe it can be but as I am no network specialist I am wondering what I would need to inform the customer of from an infrastructure.A customer has two data centres. Site A and site B. I am looking to implement a Always on High Availability Group across a Primary node in site A and a replica in Site B.The customer has stated that there network is Later three separated so there is a VLAN in each site with a /25 subnet dedicated to SQL usage. For example (10.124.x.x in site A and 10.125.x.x is site B). With a HAG the clustering features are installed across both nodes but how does it work behind the scenes,I have to describe to the customer how they need to configure the communication/networks between both sites to enable this to work. I know back in the day the a cluster needed to be on the same network/vlan but now I believe the servers can be on different networks and availability Group listeners can be on a seprecate one also.
This is not an unusual setup.
In this case. you will need to install Failover Clustering, and set up the cluster.
The quorum setup will need to be changed, depending upon the needs of the client. Is this going to be an automatic failover, with synchronous commit, or manual with async commit?
MultiSubnetFailover will need to be configured in the connection strings. That is described in the article provided in a previous post.
I suggest you read this series of articles, it spells it all out:
http://www.sqlservercentral.com/stairway/112556/
Using our setup as an example, we have a three node AG. 2 nodes are in one data center, set up as synchronous commit with an automatic failover.
These nodes, the cluster, and ONE address of the listener are all on the same subnet, XX.XX.1.1, 2, 3, 4 as an example.
The third node is in a different data center, and is manual failover/async commit.
This is on a different subnet, XX.XX.2.1
We have created a third separate vlan for the Quorum and cluster communication.
Michael L John
If you assassinate a DBA, would you pull a trigger?
To properly post on a forum:
http://www.sqlservercentral.com/articles/61537/
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